I'm playing the game wrong because an extremely overpowered warlock can crit me for 300k?

ok

you're playing the game wrong if you don't dismiss your pet before a warlock can shadowburn it, yes.
not only can you get hit very hard with havoc shadowburn, but you also give the warlock a free ember (shadowburn costs 1, and returns 2 if target dies).

just like you're playing the game wrong if you don't dismiss your pet when an spriest can sw:d it for free orbs (unless ofc the pet gets healed and doesn't die to sw:d, then it might be worth it to not dismiss it).

you're playing the game wrong if you don't dismiss your pet before a warlock can shadowburn it, yes.
not only can you get hit very hard with havoc shadowburn, but you also give the warlock a free ember (shadowburn costs 1, and returns 2 if target dies).

just like you're playing the game wrong if you don't dismiss your pet when an spriest can sw:d it for free orbs (unless ofc the pet gets healed and doesn't die to sw:d, then it might be worth it to not dismiss it).